A study has suggested that our eyesight could give one of the first indicators of potential cognitive decline, with visual problems being an early sign of dementia.
Researchers from Loughborough University have said that dementia can be predicted 12 years before it is diagnosed when visual sensitivity is lost.
The study was based on 8,623 healthy people in Norfolk, England, who were followed for many years. By the conclusion of the study, 537 participants had developed dementia, allowing researchers to see the factors that existed prior to diagnosis.
At the beginning of the study, participants were asked to take a visual sensitivity test, where “they had to press a button as soon as they saw a triangle forming in a field of moving dots,” explain the researchers.
Participants who ended up developing dementia were far slower to spot this triangle on the screen than those who did not.
Researchers believe issues with eyesight may indicate dementia “as the toxic amyloid plaques associated with Alzheimer’s disease may first affect areas of the brain associated with vision, with parts of the brain associated with memory becoming damaged as the disease progresses. So vision tests may find deficits before memory tests do.”
Alzheimer’s also affects other aspects of visual processing, such as the ability to see outlines of objects, known as contrast sensitivity. It may also affect the ability to discern between colours, with being able to see the blue-green spectrum affected in the early stages of dementia.
Another sign of Alzheimer’s is when individuals struggle to ignore distractions, when this occurs it is known as a deficit in the “inhibitory control” of eye movements.
The study also provided some evidence that those with dementia cannot process new people’s faces efficiently, meaning they don’t scan the face in a usual pattern, which is eyes to nose to mouth.
As a result of these findings, researchers are looking to explore whether doing more eye movements can therefore improve memory.
However, current research on this has provided mixed results. Some studies suggest eye movement can improve memory, but little research on using deliberate eye movements as a treatment for memory problems in older people has been conducted.
The researchers conclude: “Until cheaper and easy-to-use eye trackers are available, using eye movements as a diagnostic tool for early-stage Alzheimer’s is not possible outside the laboratory.”